The pitch error causes increase in effective diameter of bolt or screw and decrease in effective diameter of nut. If δp is the pitch error then increase in effective diameter of bolt or decrees in effective diameter of nut is given by the relation for whit-worth thread = 1.921xδp.
If δθ1 and δθ2 are errors in flank angles in opposite directions, then increase or decrease in effective diameter of bolt or nut = 0.0105xp(δθ1+δθ2).
We can also say that, the errors in pitch and angle are useful for the alternation of effective diameter. But there is a limit to the errors for accurate work. The maximum limit for the equivalent effective diameter is = 1.921xδp+ 0.0105xp(δθ1+δθ2).
The virtual diameter can be defined as the sum of simple effective diameter and maximum limit for the equivalent effective diameter.
If any difficulty is taking place in an assembly of two bolt and nut with pitch errors in bolt, by increasing the effective diameter of the nut we can assemble the two bolt and nut. In this the pitch error is distributed over the length of engagement.
If δθ1 and δθ2 are errors in flank angles in opposite directions, then increase or decrease in effective diameter of bolt or nut = 0.0105xp(δθ1+δθ2).
We can also say that, the errors in pitch and angle are useful for the alternation of effective diameter. But there is a limit to the errors for accurate work. The maximum limit for the equivalent effective diameter is = 1.921xδp+ 0.0105xp(δθ1+δθ2).
The virtual diameter can be defined as the sum of simple effective diameter and maximum limit for the equivalent effective diameter.
If any difficulty is taking place in an assembly of two bolt and nut with pitch errors in bolt, by increasing the effective diameter of the nut we can assemble the two bolt and nut. In this the pitch error is distributed over the length of engagement.
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